1. Field of the Invention
The invention relates to a coupling device, more particularly to a coupling device for interconnecting the first and second slender members.
2. Description of the Related Art
FIGS. 1 and 2 illustrate a conventional tube light 1 that comprises a plurality of slender members 11, 12. One of the slender members 11 is provided with a power plug 112. The other slender members 12 serve as lamp sections of the tube light. One of the slender members 11, 12 of an adjacent pair is provided with a pair of pin conductors 132. The other one of the slender members 11, 12 of the adjacent pair is provided with a pair of socket conductors 131 for connecting with the pin conductors 132, thereby establishing electrical connection between the adjacent pair of the slender members 11, 12. The slender members 11, 12 of every adjacent pair are further interconnected by a coupling device 2. Each coupling device 2 includes a positioning sleeve 22, an externally threaded sleeve 21 and a nut member 24. The positioning sleeve 22 is sleeved and secured on one end 122 of a first one of the slender members 12, and has a front end portion formed with a radial outward stop flange 221. The externally threaded sleeve 21 is sleeved and secured on one end 113 of a second one of the slender members 11, and has an externally threaded front end portion 211. The nut member 24 has a base ring portion 241 formed with a through-hole 242 to permit sleeving of the nut member 24 on the positioning sleeve 22, and a surrounding wall portion 243 that extends forwardly from a periphery of the base ring portion 241 and that is formed with an internal screw thread 244 for engaging the externally threaded front end portion 211 of the externally threaded sleeve
After bringing the externally threaded sleeve 21 toward the positioning sleeve 22 to interconnect the pin and socket conductors 131, 132, the coupling device 2 can be used to connect the adjacent slender members 11, 12 by engaging the nut member 24 threadedly with the externally threaded sleeve 21 until the base ring portion 241 abuts against the stop flange 221 in a fully tightened position of the nut member 24. A ring gasket 23, which is sleeved on the end 122 of the first one 20 of the slender members 12, abuts sealingly against the stop flange 221 and the front end portion 211 of the externally threaded sleeve 21 for waterproofing purposes. As such, the coupling device 2 can be used to maintain the electrical connection between the 25 adjacent slender members 11, 12.
A main drawback of the conventional coupling device 2 resides in that the nut member 24 is easily moved and loosened. When the nut member 24 is loosened, it will affect the connection between the pin and socket conductors 131, 132, and the ring gasket 23 will be loosely retained between the externally threaded sleeve 21 and the positioning sleeve 22, thereby affecting adversely the waterproofing capability of the coupling device 2.
Therefore, the main object of the present invention is to provide a coupling device of the above-mentioned type that is capable of overcoming the aforesaid drawbacks commonly associated with the prior art.
Accordingly, the coupling device of the present invention includes a positioning sleeve, an externally threaded sleeve, a nut member and a limiting member. The positioning sleeve is adapted to be sleeved and secured on one end of a first slender member, and has a radial outward stop flange at a front end portion thereof, and a radial outward stop projection at a rear end portion thereof. The stop flange and the stop projection are spaced apart from each other along an axis of the positioning sleeve. The externally threaded sleeve is adapted to be sleeved and secured on one end of a second slender member, and has an externally threaded front end portion. The nut member has a base ring portion sleeved on the positioning sleeve, and a surrounding wall portion extending forwardly from a periphery of the base ring portion. The surrounding wall portion is formed with an internal screw thread for engaging the externally threaded front end portion of the externally threaded sleeve such that the base ring portion abuts against the stop flange in a fully tightened position of the nut member. The limiting member is sleeved on the positioning sleeve, and has a front end face that abuts against the base ring portion of the nut member and a rear end face that abuts against the stop projection, thereby arresting movement of the nut member from the fully tightened position.